In addition to ampicillin, is there any benefit to the addition of either gentamicin or Bactrim when treating a patient with listeria meningitis?  

There has been a lot of misinformation in the literature for decades about the treatment of Listeria bacteremia and meningitis/encephalitis. Some of this arose based on publications of in vitro studies that claimed that "PCN and ampicillin are bacteriostatic against Listeria." This was based on dete...

I am unaware of any data supporting the addition of trimethoprim sulfa to ampicillin for this indication. In fact, the frequent recommendation to add gentamicin to ampicillin appears, to my knowledge, to be based only in vitro synergy data in the absence of confirmatory clinical data.

One of the common misconceptions is that ampicillin is not bactericidal against Listeria (like Enterococcus). This misconception arose in the 1970's since time/kill curves are customarily read at 24 hours incubation. Listeria is a slow growing organism so it is also killed more slowly in vitro by ce...